SOUTHERN 
PACIFIC LINES 
107 
The Sierra Diablo is an elevated plateau sloping gently westward 
and presenting to the east an imposing escarpment 2,000 to 2,500 feet 
high. Its highest sum- 
mit, Victorio Peak, is 
ve 
eral thousand feet by a 
long south to north 
fault or zone of faults 
that extends along its 
Victorio Peak NE: 
6432 
Horizontal scale 
3 Miles 
ical scal 
by viata e Feet 
es a | 
FicureE 18.—Section of east front of Sierra are Zz Victorio 
Peak, 18 miles north of Van B. King 
Horn, Tex. 
foot. In places the downfaulted strata are exposed dipping steeply 
to the east, as shown in Figure 18, and in the slopes 25 miles north 
of Van Horn there are small but steep escarpments in the alluvial 
fan, which probably indicate recent movements along this fault zone. 
same fossils. Some of them ean also be 
correlated with strata in the Marathon 
uplift. These limestones yore out to 
the south and west. ey appear 
in the foot of the Sierra Diablo, 25 
miles north of Van Horn, just west of 
the road to the Carlsbad Caverns. 
The Fusselman limestone contains a 
characteristic Pentamerus; the Mon- 
toya contains Columnaria, Halysites, 
and Ra- 
Piloceras, Eccyliomphalus, Hormotoma, 
and Ophileta of the Lower Ordovician. 
The Permian succession that consti- 
tutes t mountain block of the 
the 
Sierra. Diablo, the Baylor and Wylie 
Moun and some minor ridges con- 
sists mostly of limestones of various 
g 
continuous subsidence and deposition 
in the Fis img uninterrupted by uplift 
re ve incursions of coarse sedi- 
ments " Byvidently there were long 
reefs which persisted during the deposi- 
tion of thousands of feet of strata 
The position and extent of land at that 
time in the general region are not 
known. These reefs had a controlling 
effect on the sedimentation. In the 
open sea in front of them were deposited 
materials now represented by flaggy 
black limestones, siliceous shales, and 
fine sandstones which contain such 
Guadalupian fossils as Richthofenia and 
ept 
ments now represented by thinly strati- 
fied dolomite containing fusulinids in 
extreme abundance. Farther behind, 
to the west and southwest, there were 
accumulations of limy sediments with 
a fauna like that in the Hueco Moun- 
tains, including Omphalotrochus, Belle- 
rophon, uct: 
very massive limestones or dolomites, 
built of the remains of algae, bryozoans, 
and other fossils 
ieiatatns consists of es laid 
down behind the reefs. In the Sierra 
Diablo a thick body of n limestone 
constituting the lower third of the 
series is succeeded b € 
out in rounded slopes, which are sur- 
mounted by great cliffs of the reef 
limestone. Some of the relations of 
these strata are shown in Figure 18. 
In places i escarpment there is an 
abrupt transition from black limestone 
) ne. At the north end of 
the Sierra Diablo, 40 miles northwest 
